(function(doc,win){
    var docEl = doc.documentElement,resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
    recalc = function(){
        var clientWidth = docEl.clientWidth;
        if(!clientWidth) return;
        if(clientWidth>=750){
            docEl.style.fontSize = '100px';
        }
        else{
            docEl.style.fontSize = 100 * (clientWidth /750) + 'px';
        }
    };
    if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt, recalc, false);
    doc.addEventListener('DOMContentLoaded', recalc, false);
})(document,window);